My car is box stock apart from
ceramic diff balls, as I killed my diff first time out having a slipper too tight, and
ali rear hubs, which were a bling addon, not really needed. Never had an issue with the idler gear, still on my kit one, after months of use. I did swap the rear wheel nuts to serrated type, only as I'd heard of issues with the kit lock nuts, and had the serrated ones in my box. The car is fantastic out the box.
A few have replaced the shock shafts with the harder
titanium ones, but I've had no problem bending mine. I replaced the kit front springs with
AE red big bore springs, as I felt the car was better with these. Kept going back to the kit (blue) rear springs after trying lots of others.
I also used the
associated fit front axles so I could make use of my stock of B4.1/centro wheels.
It's a really good car in both mid and rear motor. It's also pretty bullet proof. I've not broken anything on it (other than the original diff plates/balls) on first assembly because the spur gear was too tight on the shaft, so the slipper didn't slip.